Production of solvents



JUIY'ZS, 1942- J. E. HARVEY, JR 2,291,309

` PRODUCTION oF soLvENTs Filed March 14, 1941 J Q@ i' /Jmk Patented July 28, 1942 UNITED STATESPATENT OFFICE PRODUCTION OF SOLVENTS Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application March 14, 1941, Serial No. 383,459

Claims. (Cl. 196-53) I controlled action of hydrogen whereby to pro- The present invention relates to the production of valuable liquids from tars of. aromatic content and fractions thereof, crude and/or refined.

This application is a continuation in part of my application Sr. No. 352,671, led August 14, 1940, for Production of solvents, copending herewith, as to all matter common to the two applications.

An object of the present invention is the subjection of tars of aromatic content and fractions thereof, crude and/or refined, to the action of hydrogen in step-wise manner, whereby to provide solvents of increased solvency, said solvents being characterized when compared to an intermediate starting material of the process, by a fractional increment in the low boiling range in excess of fractional increment in the higher boiling range.

A further object of the present invention is the production of refined solvents of lowered corrosivity, the characteristics of which are, among other things, dependent upon hydrogen supply, as hereinafter explained.

Starting materials of the present invention include tars and fractions thereof derived from coal, petroleum and gas or gases of carbon content, as for instance coke oven tar, water gas tar, gas house tar, and tars of aromatic content in general; as for instance tars of aromatic content derived from coal and fractions thereof; tars produced by cracking hydrocarbons; tars resulting from the action of hydrogen on hydrocarbons tars resulting from polymerization; high boiling extracts of carbonaceous substances; high boiling hydrocarbons of aromatic content having olefinic and/or naphthenic content.

Starting materials of the present process also include tars of aromatic content from which low boiling fractions have been removed, as for instance tars from which solvent oils have been removed. Viewed broadly, the starting materials of the present process are tars of aromatic content, fractions of said tar more viscous than the starting material due to removal of low boiling fractions from the starting material, high boil ing fractions and pitches. Starting material previously subjected to the action of hydrogen is suitable starting feed stock.

Especially suitable as starting material is high temperature coke oven tar which is available in large quantities at low prices.

The present invention may be viewed broadly as a process for the production of refined solvents of lowered corrosivity by subjecting the starting material, in step-wise manner, to the duce solvents having enhanced solvency, and as compared to the intermediate parent material, an increment of fractions in the low boiling range in excess of fractional increment in the higher boiling range.

The following examples will serve to illustrate the general principle upon which the practice of the present invention is based, as well as the process of the present invention.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the ligure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Example 1.-A sulfur bearing coal tar creosote, characterized by in excess of 1% coke residue, a specific gravity of in the order of 1.06, and substantially 25% residue above 355 C., is subjected to the action of hydrogen at 385 C. and 200 atmospheres pressure whereby to lower sulfur content, thereby' lowering corrosivity, at least providing for lowered corrosivity in the finished material ashereinafter explained. The creosote of lowered sulfur content is then passed through a high pressure reaction vessel while simultaneously flowing hydrogen therewith in the presence of a molybdenum oxide catalyst at a temperature of 400 C. and 350 atmospheres pressure. The time of contact is one hour and the flow of gas 15,000 cubic feet per barrel rened creosote. The beneficiated .creosote upon inspection will be found to have a lowered boiling range, specific gravity, coke residue and viscosity. Solvency in some of the lower fractions of the beneciated creosote will be reduced as compared to solvents extant of comparable boiling range.

The beneciated creosote is stripped to an upper limit of 300 C. and the distillate is passed through a high pressure reactor at 520 C. and 200 atmospheres pressure While contacting a molybdenum oxide catalyst. The flow of hydrogen in coordination with other process variables is so controlled as to induce a solvent having increased solvency and an increment of fractions in the lower boiling range in excess of fractional increment of fractions in the higher boiling range.

The solvent so produced may be fractionated to provide refined solvents of lowered corrosivity of any boiling range within the limits of the immediate parent material, as for instance:

Degrees centigrade The rened solvents of lowered corrosivity may serve as substitutes for the commercial solvents noted.

In the foregoing example it will be noted that the present process provides a method for contacting the starting material with hydrogen the immediate starting material, in the lower boiling range in excess of fractional increment in the higher boiling range, thus providing the refined solvent of the present process.

Example 3.-A high boiling coal tar fraction. of sulfur content, initial boiling point of substantially 245 C. is subjected to the action of hydrogen at 400 C. and 250 atmospheres pressure for such a length of time as to reduce sulfur content. The coal\tar of reduced sulfur content is then passed through a high pressure reaction chamber while simultaneously flowing hydrogen therewhereby to lower sulfur content, thereafter, contacting the material of lowered sulfur content with hydrogen whereby to produce an intermedif ate Aproduct of lowered solvency, specific gravity, boiling range, coke residue and viscosity; stripping from the beneiiciated material last named, a low boiling fraction thereof and subjecting at least a portion of said low boiling ends to the controlled action of hydrogen whereby to enhance solvency, and produce as compared to the immediate starting material an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range, thus providing the refined solvent of lowered corrosivity of the present invention.

Looked at in one manner, the present process provides a method for treating tars of aromatic content, and fractions thereof, with hydrogen in step-wise manner whereby to produce refined solvents of lowered corrosivity, said solvents being characterized by increased solvency as compared to their immediate starting material as heretofore disclosed. The step-wise action of hydrogen being characterized by providing hydrogen in flow that depolymerizes ring multiplicities thereby inducing lowered specific gravity, coke residue, boling range, solvency and viscosity, and last, by providing hydrogen in iiow that, among other things, increases solvency.

The aforenamed step-wise action of hydrogen thus provides a method for securing refined solvents of lowered corrosivity from heavy or high boiling hydrocarbons of aromatic content, said high boilers characterized by the presence of ring multiplicities of great thermal susceptibility.

Example Z.-A sulfur containing coal tar, specinc gravity 1.1641, a coke residue in excess of 5%, and in excess of 35% boiling at 355 C. is subjected to the action of hydrogen at 400 C. and 200 atmospheres pressures for such a length of time as to lower sulfur content. The coal tar of lowered sulfur content is then passed in liquid phase to a high pressure reaction chamber while simultaneously liowing therewith hydrogen at a pressure of 300 atmospheres and a temperature of 410 C.; time of contact is one hour, catalyst vanadium oxide, and flow of hydrogen 15,000 cubic feet per barrel feed stock. 'Ihe thus treated coal tar is found to have a lowered specilc gravity, viscosity, and coke residue. In some of the fractional parts of the treated coal tar there will be lowered solvency as compared to solvents extant of comparable boiling range.

The beneiiciated tar is then stripped tol an upper limit of 360 C. and the low ends thereof subjected to the action of a flow of hydrogen at 490 C. and 200 atmospheres pressure for such a length of time as to increase solvency and produce an increment of fractions, as compared to through at a temperature of 410 C. and 300 atmospheres pressure; the catalyst is molybdenum oxide and flow of hydrogen so controlled as to induce no substantial percentage of coke in the reaction chamber, nor percentage of chain structures as to preclude final solvent production as stated.

A Upon inspection the beneiiciated coal tar fraction will be found to have a lowered specific gravity, coke residue, boiling range and viscosity, and, in the case of some fractional parts of the beneiiciated material a lowered solvency as compared to solvents extant.

The beneciated material is stripped at 290 C. and the distillate subjected to the action of hydrogen at 525 C. and 200 atmospheres pressure, iiow of hydrogen 4,000 cubic feet per barrel feed and the time so controlled as to provide an increment of low boiling fractions in excess of fractional increment in the higher boiling range. The solvency of the finally processed material is in excess of the solvency of the immediate starting material. The time in the last step may be a fractional part of a minute or more.

The residue incidental to the stripping steps may be recycled or used as an article of commerce of enhanced value, as for instance binders, plasticizers or the like.

The starting material of high carbon content, as for instance coke oven tar is characterized by, in its raw state, such a percentage of high moiecular complexes or polymerized products that the refined solvents of the present invention are not possible of. manufacture therefrom directly, but must be produced in step-wise manner, as heretofore explained, whereby among other things, the action of hydrogen depolymerizes said molecular complexes contained in the starting material.

- The depolymerized or partially depolymerized tar or fractions thereof of lowered sulfur content is then stripped of a percentage of its low ends whereby to provide the intermediae parent material of the reiined solvents of lowered corrosivity, said refined solvents being characterized, as compared to the immediate starting material, by an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range; the residue incidental to said stripping may, because of its depolymerized or partially depolymerized condition serve as recycle material to the end that conversion of the starting material in the percentage finally remaining liquid approach volume for volume of the starting material into the refined solvents of the present invention.

In the conversion of starting material, partially or approaching unity, into the refined solvents of lowered corrosivity, temperatures as low as 300 C. may be employed; pressures as low as 50 atmospheres may be used. However, temperatures and pressures of an increased range provide ,better commercial Practice. vThe time element is desirably that period which affords commercial recoveries of the products of, and incidental to, the present invention. Temperatures are preferred that cause no substantial amount of coking.

Gas flows are usually held in excess of 3,000` cubic feet per barrel feed treated. In the stepwise application of hydrogen a few trials when using any of the starting materials will determine the gas ow when coordinated with the selected temperature and pressure conditions to effect said depolymerization. The gas flow in this instance may be a variable quantity because of the varying ranges of coordinated temperature and pressure that may be selected. When using a chosen coordination of temperatures and pressures, a few trials will readily determine the gas flow that provides depolymerizing conditions to the end that solvency, specic gravity, viscosity and boiling range are lowered.

Concerning the gas iiow that increases solvency and provides an increment of low boiling fractions in excess of fractional increment in the higher boiling range, said gas flow is held at that point which induces no percentage of final liquid chain structures or the like that would preclude the enhanced solvents of the present invention. For a given coordination of temperature and pressure, the gas flow in the lastinstance is lower than the gas flow in the preceding instance.

Using some starting materials a gas flow of 10,000-15,000 cubic feet per barrel feed, or higher, has proven satisfactory for depolymerizing conditions, and, gas flows of in the order of 6,000-8,000 or lower when increasing solvency have proven satisfactory.

Viewed broadly the hydrogen ow in the instance of obtaining depolymerizing conditions may be lower than 10,000 cubic feet per barrel feed, and the flow in the last instance is held at that point that increases solvency.

In the hydrogen action that reduces sulfur content, the action of hydrogen may be effected in an intermittent autoclave or in a continuous plant, and in the event of continuous practice, the gas flow is maintained so as to assist in sulfur reduction and the removal thereof from the reaction zone, the while inducing no substantial percentage of carbon, nor percentages of liquid chain structures that would preclude the provision of the refined solvents of superior solvency of the present process.

By the term beneficiated as used herein and in the appended claims is meant the starting material at least once subjected to the action of hydrogen in accordance with the present process.

By the upper boiling range is meant, as an example, the upper half of the boiling range.

Erample 4.-It has been discovered that when subjecting certain mixtures of refined coal tar fractions to the action of hydrogen in accordance with the present process for thel production of solvents and/or plasticizers the formerly accepted teaching that product increment, depolymerization and/or hydrogen absorption are linear functions of the time, is not followed.

When subjecting a mixture of crude coal tar fractions boiling predominantly above 250 C. or 275 C. to the action of hydrogen, research has disclosed that the newly induced products, depolymerization and/or hydrogen absorption are linear functions of the time. As an example, when the above mixture of crude coal tar fractions is subjected to the action of hydrogen for 2, 5, and 8-hour periods, the newly induced products, depolymerization and/or hydrogen absorption were linear functions of the time element.

One of the preferred starting materials of the present process is a mixture of refined coal tar fractions boiling predominantly above 355 or 380 C. Such a starting material is conveniently the nal residue resulting from evaporating coal tar to dryness or substantial dryness and then stripping wood preservative from the distillate. This final residue mass of refined coal tar fractions is an especially suitable refined pitch to be used as starting material of the present process. However, in contradistinction to the mixture of crude coal tar fractions boiling predominantly above 250 or 300 C., when the aforenamed preferred starting material is subjected to the action of hydrogen for production of solvents and/or plasticizers, the newly induced fractions, depolymerization and/or hydrogen absorption are not, as described for the other mixture of crude tar fractions, linear functions of the time. A critical period of treatment by or with hydrogen exists, which if exceeded causes loss of newly induced fractions, polymerization and/or lessened hydrogen absorption on certain fractions of the preferred starting material under treatment.

The critical time element because of the obvious possible variations in the characteristics of the aforenamed refined pitch cannot be spoken of as an arbitrary figure. It can be stated, however, that if the refined coal tar pitch were to be subjected to the action of hydrogen for such a length of time, which for other crude tar fractions would illustrate that the newly induced fractions, depolymerization and/or hydrogen absorption were linear functions of the time element, loss of induced products, polymerization and/or lessening of hydrogen absorption would occur. When treating the refined pitch by or with hydrogen, the critical time element is in the order of about three hours.

In the disclosures made herein and in the appended claims distillate removal of low boiling portions from the beneficiated material is considered the equivalent of fractional removal by gas movement, solvent action or the like. The converse also obtains.

A sulfur bearing refined coal tar pitch chosen from the group boiling predominantly above, and above, 355 C., characterized by the coke residue in excess of substantially 2%, a specific gravity greater than 1 and content of ring multiplicities is subjected to the action of hydrogen at 400 C. and 225 atmospheres pressure whereby to lower sulfur content, thereby lowering corrosivity, at least providing for lowered corrosivity in the finished material as hereinafter explained. The action of hydrogen for the lowering of sulfur content is so controlled as to induce no substantial percentage of low boiling fractions, as for instance low boiling fractions indicated in the foregoing data.

The rened coal tar pitch of lowered sulfur content is then passed in liquid phase through a high pressure reaction vessel while simultaneously flowing hydrogen therewith in the presence of an oxide catalyst chosen from the group comprising the sixth and eighth periodic groups, or from a group providing diicultly reducible oxides, at a temperature of 435 C. and 325 atmospheres pressure. The time of contact is two hours and the flow of gas 15,000 cubic feet per barrel material treated. The beneciated ,material upon inspection will be found to haverlowered boiling points, solvency, specific gravity, coke residue and viscosity. Solvency in some of the lower fractions of the beneficiated material will be reduced as compared to solvents extant of comparable boiling range.

The beneficiated refined coal tar pitch is stripped to an upper limit of 290 C. and the distillate is passed through a high pressure reactor at 535 C. and 200 atmospheres pressure. The flow of hydrogen is coordinated with other process variables so as to provide a final product having increased solvency and an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range. The material of induced solvency may be fractionated to provide solvents of various boiling ranges as for instance some of the ranges indicated elsewhere herein.

The residue resulting from the provision of the intermediate starting -material may be recycled if desired for further solvent production. The residue is of a more liquid nature than a comparable cut on the starting material indicating that the high boiling ends which may be described as including multiplicity of ring structures had been, at least, either saturated or partially saturated, thus providing the initial step in the step-wise conversion of substantially the entirety of the rened coal tar pitch remaining liquid under process conditions into the rened solvents of lowered corrosivity of the present process.

In the instance of the intermediate starting material recovered to an upper limit of 290 C., as above described, the solvent cut of the finally processed material may be divided to provide solvents of various boiling ranges as may be dictated by necessity. When providing the intermediate starting material of the present process, and in the event such provision is made by taking a deep cut on the beneficiated refined pitch, the deep cut after further hydrogen action, as heretofore described, may provide high boiling fractions having plasticizing properties.

When subjecting a rened coal tar pitch to the action of hydrogen for the production of solvents in accordance with the present process, the hydrogen action characterized by lowered coke residue is controllably held at or below the critical time period, and if such is exceeded adverse reaction will occur. As an example, if the critical time period is exceeded, instead of fractional increment, depolymerization and/or hydrogen absorption being linear functions of the time element, the reverse will obtain. In other words, if the critical time period is exceeded, fractional increment, depolymerization and/or hydrogen absorption will not be linear functions of the time element, it having been found, among other things, that a period in excess of that which is critical will provide for loss of fractional increment and/ or polymerization.

As stated above the critical time element in the instance of treating the refined coal tar pitch with hydrogen is in the order of about three hours, and the present process is predicated on the employment of the critical, and preferably less than the critical, time element.

The refined solvents of lowered corrosivity as owing from the conversion products of the refined pitch are of superior quality and are characterized vby a preponderance of ring structures.

After the `starting tar has been subjected to depolymerizing action, the stripping step may be effected at any point selected within a wide range to provide a cut capable of providing, after further processing, substitutes for the boiling ranges of benzol, toluol, xylol, the various naphthas and the various plasticizers.

Thus, the depolymerized starting material may be cut according to the need at hand, said cut being then subjected to the action of hydrogen that increases solvency as heretofore explained.

The catalysts of the present invention are oxides; as for instance oxides of metals of the 6th and 8th periodic groups; the oxides of other groups may be used, however, dicultly reducible oxides are preferred. The catalyst in any form may be employed, as for instance pellets, comminuted, supported on carriers or the like; in any effective form.

If desired, comminuted catalyst may be used in the hydrogen step characterized by depolymerization, and in the step characterized by solvency increase, a rigid catalyst may be used.

By multiplicity of rings, high molecular complexes and polymerized products are meant high boiling fractions of aromatic content, a portion of which at least may be viewed as ring multiples; or, said terms, any or all, may be used to describe high boiling fractions of the starting material which because of high carbon content are especially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting material to the process of the present invention, it may be desirable prior to the depolymerizing step, or the sulfur reduction step, to at least partially depolymerize the molecular complexes by use of a solvent. Said solvent may be added in a small amount, or up to volume for volume or more. Refractory solvents are desirable, but others more susceptible to the reactions inherent in and to the present process are usable.

Concerning solvents, it may be said that tar in itself, as for instance coke oven tar, is constituted of high molecular complexes dissolved, cut back or depolymerized with a solvent, said solvent being the lower boiling fractions of said tar.

The action of hydrogen may be effected in one or more cycles, in one or several chambers, with or without releasing the pressure, and with or without variation of process controls.

Various modes of practicing the present invention are possible, as for instance, the depolymerized starting material may be stripped as for instance by gas movement; the low ends thus stripped may then, with or without releasing pressure, be subjected to the further action of hydrogen. Or, the desired stripped material may be obtained by partial release of pressure which would correspond to the fractional recovery desired or predetermined.

The process may be practiced in an autoclave and/or a single reaction chamber, a series thereof, a parallelism thereof including a multiplicity thereof.

The refined solvent of the present invention may be fractionated to provide solvents and/or plasticizers of various boiling ranges, and in the instance where solvents are processed from a deep cut on the depolymerized material, the highest boiling fraction thereof or others, may serve a-s a substitute for certain plasticizers.

In the first cycle of hydrogen action that reduces sulfur content, said reduction of sulfur may be accomplished in the presence of a catalyst. Catalysts effective in the presence of hydrogen are usable, as for instance the oxides and/or suldes of molybdenum. vanadium, uranium, cobalt, tin, manganese, tungsten, or the like.

In the disclosures herein made the removing of low boiling fractions by gas movement or pressure release is considered the equivalent of distillation.

When reference is made to high molecular complexes contained in the starting material., and when the starting material contains low boiling fractions that are not considered high molecular complexes, it is of course obvious that the high molecular complexes contained in the starting material are to a certain extent depolymerized by the solvent present.

It will be seen that by reduction of sulfur content of the material under treatment during any stage of hydrogen action, the oXide catalyst used during subsequent stages is at least partially protected from the effect of the sulfur.

The evaluation of solvent power is conveniently accomplished by finding the well-known aniline point or kauri-butanol number. The evaluation of plastioizing properties is conveniently accomplished by recourse to methods suggested in Chapter VI, The Technology of Solvents by Dr. Otto Jordon, Manheim, Germany, translated by Alen D. Whitehead, Chemical vPublishing Company of New York, Incorporated, New York, New York.

Minor changes may be made without departing from the spirit of the invention.

I claim:

1. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionatin'g the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen at a temperature and pressure of at least about 385 C. and 50 atmospheres, respectively, and for such a time as to lower sulfur content, whilst precludin-g substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst at a temperature and pressure in excess of about 400 C. and 50 atmospheres respectively, for a period not in exc-ess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneiciated material; and subjecting at least a portion of said stripped fractions to the action of a relatively low flow of hydrogen at a pressure of at least about 50 atmospheres and a temperature selected between about Li90-535 C. to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range to produce a solvent.

2. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; subjecting at least a portion of said stripped fractions to the action of a relatively low flow of hydrogen to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range; and fractionating the last named beneficiated material to segregate a solvent.

3. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur cont-ent to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; subjecting at least a portion of said stripped fractions to the action of a relatively low ow of hydrogen to provide an increment of fractions in the lower boiling range in excess of fractional increment in th-e higher boiling range; and fractionating the last named beneliciated material to provide a solvent boiling predominantly between C. and 150 C.

4. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen at a temperature and pressure of at least about 385 C. and 50 atmospheres, respectively, and for such a time as to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high ow of hydrogen in the presence of an oxide catalyst at a pressure in excess of about 50 atmospheres and a temperature in excess of about 400 C. for a period not in excess of about three hours, whereby to avoid polymerization; stripping newly induced fractions from the beneficiated material; and subjecting at least a portion of said stripped fractions to the action of a relatively low flow of hydrogen at a pressure at least about 50 atmospheres and a temperature selected between about 490-535D C. to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range, to produce a solvent.

5. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen at a temperature and 'pressure of at least about 385 C. and

50 atmospheres, respectively, and for such a time as to lower sulfur content, whilst precluding substantial low boiling fractiona1 increment; subjecting the material of lowered sulfur content t0 the action of a relatively high flow of hydrogen in the presence of an oxide catalyst at a temperature and pressure in excess of about 300 C., and about 50 atmospheres, respectively, for a period not in excess of about three hours, whereby to avoid lowered hydrogen absorption; stripping 10 newly induced fractions from the beneciated material; and subjecting at least a portion of said stripped fractions to the action of arelatively low iiow of hydrogen at a pressure at least about 50 atmospheresand a temperature selected between about 490-535" C. to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range, to produce a solvent.

JACQUELIN E. HARVEY, JR. 

